title: Human DNA polymerase eta activity and translocation is regulated by phosphorylation.
abstract: Human DNA polymerase eta (pol eta) can replicate across UV-induced pyrimidine dimers, and defects in the gene encoding pol eta result in a syndrome called xeroderma pigmentosum variant (XP-V). XP-V patients are prone to the development of cancer in sun-exposed areas, and cells derived from XP-V patients demonstrate increased sensitivity to UV radiation and a higher mutation rate compared with wild-type cells. pol eta has been shown to replicate across a wide spectrum of DNA lesions introduced by environmental or chemotherapeutic agents, or during nucleotide starvation, suggesting that the biological roles for pol eta are not limited to repair of UV-damaged DNA. The high error rate of pol eta requires that its intracellular activity be tightly regulated. Here, we show that the phosphorylation of pol eta increased after UV irradiation, and that treatment with caffeine, siRNA against ATR, or an inhibitor of PKC (calphostin C), reduced the accumulation of pol eta at stalled replication forks after UV irradiation or treatment with cisplatin and gemcitabine. Site-specific mutagenesis (S587A and T617A) of pol eta at two putative PKC phosphorylation sites located in the protein-protein interaction domain prevented nuclear foci formation induced by UV irradiation or treatment with gemcitabine/cisplatin. In addition, XP-V cell lines stably expressing either the S587A or T617A mutant form of pol eta were more sensitive to UV radiation and gemcitabine/cisplatin than control cells expressing wild-type pol eta. These results suggest that phosphorylation is one mechanism by which the cellular activity of pol eta is regulated.
authors.affiliation: Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202.
authors.forename: Yih-Wen
authors.initials: YW
authors.lastname: Chen
authors.forename: James E
authors.initials: JE
authors.lastname: Cleaver
authors.forename: Zafer
authors.initials: Z
authors.lastname: Hatahet
authors.forename: Richard E
authors.initials: RE
authors.lastname: Honkanen
authors.forename: Jang-Yang
authors.initials: JY
authors.lastname: Chang
authors.forename: Yun
authors.initials: Y
authors.lastname: Yen
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Chou
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D002110:Caffeine / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000235:genetics; D002460:Cell Line; D004249:DNA Damage; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020125:Mutation, Missense; D010766:Phosphorylation / Q000528:radiation effects; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D002110:Caffeine; D018797:Cell Cycle Proteins; D004259:DNA-Directed DNA Polymerase; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; C576597:ATR protein, human; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases